1. Field of the Invention
The present invention relates to a fiber reinforced polypropylene-based composite material.
2. Description of the Related Art
It is well known that a fiber reinforced composite material wherein reinforcing fibers are covered with a matrix resin has excellent mechanical properties which can not be exhibited by a single material.
For example, polypropylene-based composite materials reinforced with glass fibers, carbon fibers or the like are known as typical composite materials. In such composite materials, reinforcing fibers provide mechanical strength such as a tensile modulus and a matrix resin adheres to the reinforcing fibers to wrap them. Thus, forms of products are provided.
In the aforementioned composite materials wherein the reinforcing fibers and the matrix resin are formed from different kinds of materials, however, it is difficult to improve adhesiveness between the reinforcing fibers and the matrix resin. For example, in the case of the above-mentioned polypropylene-based composite material reinforced with glass fibers, the surfaces of the glass fibers have been required to be coated with a resin or a finishing agent that adheres to a polypropylene-based resin easily or a maleic acid-modified polypropylene-based resin which has good adhesiveness to glass fibers has been required to be used as the matrix resin.
Moreover, in the case of polypropylene-based composite materials in which glass fibers or carbon fibers are mixed or inserted, it is very difficult for the glass fibers or carbon fibers to be separated from the composite materials. Therefore, when the composite materials are used through recycling, they can be used only as glass fiber reinforced or carbon fiber reinforced polypropylene-based resin. This results in a problem in that products which can be recycled are limited.
Under these circumstances, the present inventors have studied to develop a fiber reinforced composite material that exhibits a sufficient adhesiveness between reinforcing fibers and a matrix resin and has excellent mechanical properties without being subjected to any special treatment and whose products can be directly recycled and used without the removal of the reinforcing fibers. As a result, they have reached the present invention.
The present invention provides a fiber reinforced polypropylene-based composite material comprising reinforcing fibers and a matrix resin, wherein the reinforcing fibers and the matrix resin are made of different polypropylene-based resins and wherein a melting point, Tm(F), of the polypropylene-based resin which is the material forming the reinforcing fibers and a melting point, Tm(M), of the polypropylene-based resin which is the matrix resin satisfy Tm(F)xe2x88x92Tm(M) greater than 10xc2x0 C.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
Throughout this specification and the claims which follow, unless the context requires otherwise, the word xe2x80x9ccomprisexe2x80x9d, and variations such as xe2x80x9ccomprisesxe2x80x9d and xe2x80x9ccomprisingxe2x80x9d, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integer or step.